Hello everyone. I'm new here. I have a practice test that I'm working on for my linear algebra class and I sorta get the gist of determining whether or not something is a subspace or not but I'm having trouble with this one:

I did terrible in Calc 2 so the whole derivative thing isn't too familiar to me.

I also have some T/F questions on it. I have guesses but nothing I know for a fact.

True/False?:

1. P2 is a Subspace of P3 (I think it's true)

2. D[0,1], the set of all differential functions over [0,1] is a subspace of C[0,1] (I think it's true)

3. {ax^2 + bx + c : b = 0} is a subspace of P2 (I think it's true....or maybe not)